“I should be going 80 [kmh] and I’m going 190 [kmh],” the driver of the train that crashed in Santiago de Compostela in northwestern Spain on July 24 reportedly told his company’s emergency service on the phone after the accident. The train derailed on a treacherous curve, killing at least 78 and injuring 130. The conductor, Francisco Jose Garzon Amo, reportedly acknowledged on the call to his colleagues that he had been going more than double the speed limit of roughly 50 miles per hour. That raises a key question: Even if Garzon was reckless how is it that a technologically advanced train like the one he was driving didn’t automatically slow down?

Today, the conductor, hospitalized and under arrest on charges of recklessness, will testify before an investigating judge attempting to determine the answer to that question—as well as deciding whether Garzon should be charged with the murder of 80 people. In Garzon’s favor are the 30 years he has worked as a conductor, and his previously clean record. Today, Juli Gómez-Pomar, president of Renfe, Spain’s rail company, told the press that trains passed through the place where the accident occurred “six times a day, and that conductor had done it sixty times before.”

But probably working against Garzon is a Facebook page, since closed, in which months earlier he posted a photograph of a speedometer marking 200 kilometers, and exulted: “What a joy it would be to run side by side with the Civil Guard, then pass them, setting off their radar guns. That would be quite a fine for Renfe (the Spanish train company), he he.”

Although the train that Garzon was driving, a series 730 train made by Bombardier and Talgo and used by Renfe for its Alvia service, is not as fast as Spain’s AVE bullet train, it still regularly reaches 240 kilometers an hour. Preliminary information, including closed circuit footage of the crash, suggest that the train was going at around 190 kmh (118 mph) when it derailed. As the train approached the curve its front engine jumped the track, slamming into a retaining wall, breaking apart the rest of the convoy, and causing several cars to flip over. The penultimate car was completely destroyed, and the rear engine burst into flame. Investigators are compiling and assessing evidence, including data collected from the train’s “black box.”

But even if Garzon was inclined to push the train too fast how could such a technologically advanced system not offer any protection against human error?

Santiago Pino Jimenez, director of communication for the Spanish Rail Conductors Union (SEMAF) believes it does and that there was a system error. “Human error alone could not account for an accident of this magnitude,” he says. “Either the wrong system was being used, or there was a flaw in the system.”

One possible problem may lie with the train’s automatic braking system. Like the bulk of European high-speed lines, most of the Madrid-to-Ferrol track, on which the accident occurred, is controlled by an oversight mechanism called ERMTS, which essentially prevents the train from exceeding set speed limits. However, according to Spanish press reports, the section of track along which the accident occurred did not utilize ERMTS, but rather an older warning and automatic braking system called ASFA. That system operates only at certain points on the track rather than at every point, as ERMTS does.

In the coming days, interviews with Garzon and the other surviving crew members, as well as information retrieved from the black box, will help investigators determine the accident’s cause. Until then, Stephen Ward, an 18-year-old Mormon missionary from Utah who was onboard, and traveling to Ferrol to start his mission, didn’t want to speculate. Discharged from the hospital but sporting stitches in his scalp and a neckbrace, he was grateful that he had escaped a worse fate. “If it turns out that the conductor was to blame, I hope he’s held responsible. And if he wasn’t, I hope it’s not held against him. But it would be good if this never happened again.”